WLAN user fixed network accessing method and system

ABSTRACT

A method for a Wireless Local Area Network (WLAN) user to access a fixed network is disclosed, which includes: after the WLAN user is authenticated successfully, a Broadband Network Gateway (BNG) sends obtained user subscription information to a WLAN device; and after the WLAN device performs related configuration according to the user subscription information, a WLAN user terminal accesses a network. A system for a WLAN user to access a fixed network is also disclosed. The present disclosure can solve the problem that a WLAN network cannot perceive the user subscription information and further cannot provide differentiated services based on different users and different subscription information because a WLAN user passes through BNG authentication.

TECHNICAL FIELD

The present disclosure relates to the technical field of datacommunication network, and in particular to a method and system for aWireless Local Area Network (WLAN) user to access a fixed network.

BACKGROUND

With the rapid development of Internet application and intelligentterminal, the requirement of users for accessing, through variousintelligent terminals, such as smart phone and tablet computer, theInternet to work anytime and anywhere is widely popularized, one of themost important methods is that users access a network through a WLANnetwork.

As shown in FIG. 1, a traditional WLAN network includes an Access Point(AP), an Access Controller (AC), an Authentication, Authorization andAccounting (AAA) server and other network elements; a user terminal,after being authenticated by the AAA server, can access a networkthrough the AP and the AC; the AC manages and controls the AP devicethrough a Control And Provisioning of Wireless Access Points Protocol(CAPWAP). With the development of network convergence trend, convergenceof the WLAN network and a fixed broadband network becomes one of futuremainstream trends; as shown in FIG. 2 and FIG. 3, all types of userterminals access the fixed broadband network through the WLAN networkand a wired link; user authentication and service control are performedby a Broadband Network Gateway (BNG), and the AC of the WLAN networkonly takes charge of management and service configuration of the AP. Inthe meantime, the requirement of emerging Internet applications tonetwork quality becomes higher and higher, operators put forward higherrequirements for safety and quality of service of the WLAN network, andrequire that the WLAN network can provide bandwidth assurance, securityencryption and other functions, and can provide different levels ofservices based on subscription situations of different users. Under thesituation that the BNG device uniformly performs WLAN and wiredbroadband user authentication, the AC cannot perceive user subscriptionsituation, which causes that the WLAN network cannot provide securityand bandwidth assurance and other functions based on user subscriptioninformation.

SUMMARY

In view of this, the present disclosure provides a method and a systemfor a WLAN user to access a fixed network, for at least solving theproblem that a WLAN network cannot perceive user subscriptioninformation and further cannot provide differentiated services based ondifferent users and different subscription information because a WLANuser passes through BNG authentication.

The technical solutions of the present disclosure are implemented asfollows.

The present disclosure provides a method for a WLAN user to access afixed network, including:

after the WLAN user is authenticated successfully, a BNG sends obtaineduser subscription information to a WLAN device; and

after the WLAN device performs related configuration according to theuser subscription information, a WLAN user terminal accesses a network.

Preferably, before the authentication of the WLAN user, the method mayfurther include:

configuring the BNG as an authentication server end, and configuring theWLAN device as an authentication client end.

Preferably, the WLAN device may be an AC or an AP.

Preferably, after the WLAN user is authenticated successfully, while theBNG sends the obtained user subscription information to the WLAN device,the method may further include:

the BNG sends the user subscription information to the WLAN userterminal through an Extensible Authentication Protocol (EAP)authentication success message.

Preferably, when the WLAN device is the AC, the BNG sending the obtaineduser subscription information to the WLAN device may include: the BNGconfirms the AC to which the WLAN user terminal belongs, and sends theuser subscription information to the AC through a Radius CoA message ora Diameter CCA message; and the AC sends the user subscriptioninformation to the AP by means of CAPWAP or Technical Report-069(TR-069); or,

when the WLAN device is the AP, the BNG sending the obtained usersubscription information to the WLAN device may include: the BNGconfirms the AP to which the WLAN user terminal belongs, and sends theuser subscription information to the AP through the Radius CoA messageor the Diameter CCA message.

Preferably, the BNG confirming the AC or the AP to which the WLAN userterminal belongs may include: the BNG confirms the AC or the AP to whichthe WLAN user terminal belongs through a Media Access Control (MAC)address of the WLAN user terminal and/or user side logical interface orphysical port information of the BNG.

Preferably, the WLAN device performing related configuration accordingto the user subscription information may include:

the AP performs a bandwidth and priority configuration of an airinterface according to a user subscription bandwidth and a priority inthe user subscription information; and, the AP and the WLAN userterminal conduct a key negotiation according to an encryption key in theuser subscription information to obtain an encryption key PTK;

the encryption key is a Pre-shared Key (PSK) or a Pairwise Master Key(PMK).

Preferably, after the WLAN device performs related configurationaccording to the user subscription information, the method may furtherinclude: the WLAN user terminal applies to the BNG for an IP addressthrough a Dynamic Host Configuration Protocol (DHCP) protocol, andaccesses a network after obtaining the IP address; or,

before the WLAN user authentication, the method may further include: theWLAN user terminal applies to the BNG for an IP address through the DHCPprotocol.

Preferably, after the WLAN user accesses a network, the method mayfurther include:

the WLAN user accesses a portal server, and changes the usersubscription information on line;

the portal server sends the changed user subscription information to anAAA server; and

the AAA server sends the changed user subscription information to theBNG through the Radius CoA message or the Diameter CCA message.

Preferably, the method may further include: the BNG sends the changeduser subscription information to the WLAN device, specificallyincluding:

when the WLAN device is the AC, the BNG sends the changed usersubscription information to the AC through the Radius CoA message or theDiameter CCA message; and, the AC sends the user subscriptioninformation to the AP by means of CAPWAP or TR-069; or,

when the WLAN device is the AP, the BNG sends the changed usersubscription information to the AP through the Radius CoA message or theDiameter CCA message.

The present disclosure also provides a system for a WLAN user to accessa fixed network, including: a BNG and a WLAN device;

the BNG is configured to, after the WLAN user authentication issuccessful, send the obtained user subscription information to the WLANdevice; and

the WLAN device is configured to perform related configuration accordingto the user subscription information.

Preferably, the BNG is further configured to, after the WLAN userauthentication is successful, send the user subscription information tothe WLAN user terminal through the EAP authentication success messagewhile sending the obtained user subscription information to the WLANdevice.

Preferably, when the WLAN device is the AC, the BNG is furtherconfigured to confirm the AC to which the WLAN user terminal belongs,and send the user subscription information to the AC through the RadiusCoA message or the Diameter CCA message; the AC is configured to sendthe user subscription information to the AP by means of CAPWAP orTR-069; or

when the WLAN device is the AP, the BNG is further configured to confirmthe AP to which the WLAN user terminal belongs, and send the usersubscription information to the AP through the Radius CoA message or theDiameter CCA message.

Preferably, the BNG is further configured to confirm the AC or the AP towhich the WLAN user terminal belongs through the MAC address of the WLANuser terminal and/or the user side logical interface or physical portinformation of the BNG.

Preferably, the AP is further configured to perform a bandwidth andpriority configuration of an air interface according to the usersubscription bandwidth and priority in the user subscriptioninformation, and conduct key negotiation with the WLAN user terminalaccording to an encryption key in the user subscription information toobtain the encryption key PTK;

the encryption key is the PSK or the PMK.

Preferably, after the user subscription information is changed,

when the WLAN device is the AC, the BNG is further configured to sendthe changed user subscription information to the AC through the RadiusCoA message or the Diameter CCA message; the AC is further configured tosend the user subscription information to the AP by means of CAPWAP orTR-069;

or when the WLAN device is the AP, the BNG is further configured to sendthe changed user subscription information to the AP through the RadiusCoA message or the Diameter CCA message.

The present disclosure provides a method and a system for a WLAN user toaccess a fixed network, wherein the method includes: after the WLAN useris authenticated successfully, a BNG sends the obtained usersubscription information to a WLAN device; and after the WLAN deviceperforms related configuration according to the user subscriptioninformation, a WLAN user terminal accesses a network. Thus, the problemthat a WLAN network cannot perceive the user subscription informationand further cannot provide differentiated services based on differentusers and different subscription information because a WLAN user passesthrough BNG authentication can be solved. The means that the WLAN deviceperforms related configuration according to the user subscriptioninformation can provide different levels of services for different usersin a WLAN network and a fixed broadband converged network, therebyimproving the quality of service of WLAN services and the flexibility ofservice bundles.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a topological diagram of a traditional WLAN network;

FIG. 2 is a network topology diagram of a convergence mode of a WLANnetwork and a fixed broadband network;

FIG. 3 is a network topology diagram of another convergence mode of aWLAN network and a fixed broadband network;

FIG. 4 is a flowchart of WLAN user fixed network access in an embodimentof the present disclosure;

FIG. 5 is a flowchart of a first embodiment of the present disclosure;

FIG. 6 is a flowchart of a second embodiment of the present disclosure;

FIG. 7 is a flowchart of a third embodiment of the present disclosure;and

FIG. 8 is a structural diagram of a system for a WLAN user to access afixed network in an embodiment of the present disclosure.

DETAILED DESCRIPTION

The present present disclosure provides a method for a WLAN user toaccess a fixed network; as shown in FIG. 4, the method includes thefollowing steps:

Step 401: after WLAN user authentication is successful, a BNG sendsobtained user subscription information to a WLAN device; and

Step 402: after the WLAN device performs related configuration accordingto the user subscription information, a WLAN user terminal accesses anetwork.

Preferably, before performing the WLAN user authentication, the methodfurther includes: the BNG is configured as an authentication server end,and the WLAN device is configured as an authentication client end. ARadium protocol, or a Diameter protocol, or a Tacacs protocol can beconfigured as an authentication protocol between the BNG and the WLANdevice.

Preferably, the WLAN device is an AC or an AP.

Preferably, after the WLAN user authentication is successful, while theBNG sends the obtained user subscription information to the WLAN device,the method further includes: the BNG sends the user subscriptioninformation to the WLAN user terminal through an EAP authenticationsuccess message.

Preferably, when the WLAN device is the AC, the BNG sending the obtaineduser subscription information to the WLAN device includes: the BNGconfirms the AC to which the WLAN user terminal belongs, and sends theuser subscription information to the AC through a Radius attributechange CoA message or a Diameter CCA message; and the AC sends the usersubscription information to the AP by means of CAPWAP or CPE networkmanagement protocol TR-069 (one of the technical reports from theBroadband Forum); or,

when the WLAN device is the AP, the BNG sending the obtained usersubscription information to the WLAN device includes: the BNG confirmsthe AP to which the WLAN user terminal belongs, and sends the usersubscription information to the AP through the Radius CoA message or theDiameter CCA message.

Preferably, the BNG confirming the AC or the AP to which the WLAN userterminal belongs includes: the BNG confirms the AC or the AP to whichthe WLAN user terminal belongs through a MAC address of the WLAN userterminal and/or user side logical interface or physical port informationof the BNG.

Preferably, the WLAN device performing related configuration accordingto the user subscription information includes:

the AP performs a bandwidth and priority configuration of an airinterface according to the user subscription bandwidth and priority inthe user subscription information; and, the AP and the WLAN userterminal conduct key negotiation according to an encryption key in theuser subscription information to obtain the encryption key PTK; wherein,the encryption key is the PSK or the PMK.

Preferably, after the WLAN device performs related configurationaccording to the user subscription information, the method furtherincludes: the WLAN user terminal applies to the BNG for an IP addressthrough the DHCP protocol, and accesses a network after obtaining the IPaddress; or,

before the WLAN user authentication, the method further includes: theWLAN user terminal applies to the BNG for an IP address through the DHCPprotocol.

Preferably, after the WLAN user accesses a network, the method furtherincludes:

the WLAN user accesses a portal server, and changes the usersubscription information on line;

the portal server sends the changed user subscription information to anAAA server; here, the user subscription information can be sent by usinga private protocol message between the portal server and the AAA server;

the AAA server sends the changed user subscription information to theBNG through the Radius CoA message or the Diameter CCA message.

Preferably, the method further includes: the BNG sends the changed usersubscription information to the WLAN device, specifically including:

when the WLAN device is the AC, the BNG sends the changed usersubscription information to the AC through the Radius CoA message or theDiameter CCA message; and, the AC sends the user subscriptioninformation to the AP by means of CAPWAP or TR-069; or,

when the WLAN device is the AP, the BNG sends the changed usersubscription information to the AP through the Radius CoA message or theDiameter CCA message.

Wherein, the BNG includes Broadband Remote Access Server (BRAS), ServiceRouter (SR), Network Access Server (NAS) and so on.

By using the method above, different levels of services can be providedfor different users in the WLAN network and the fixed broadbandconverged network, thereby improving the quality of service of WLANservices and the flexibility of service bundles

The above technical solutions of the present disclosure are elaboratedthrough specific embodiments.

Embodiment 1

A scenario that the embodiment is applicable is shown in FIG. 2; the ACis between the AP and the BNG; a data message after the successful userauthentication flows through the AC, and the WLAN device is the AC; asshown in FIG. 5, the flow of WLAN user fixed network access includes thefollowing steps.

Step 501: The following configurations are performed in the AC:configuring the AC as the authentication client end, and configuring theBNG as the authentication server end of the AC.

Step 502: The following configurations are performed in the BNG:configuring the BNG as the authentication server end, and configuringthe AC as the authentication client end of the BNG.

Step 501 and Step 502 are executed in a random order.

Step 503: The user terminal (namely the WLAN user) sends an EAPoL-Startmessage to the BNG, so as to initiate an authentication request.

Step 504: The BNG sends an EAP-Request/Identity message to the userterminal, so as to require the user terminal to report a user name.

Step 505: The user terminal sends an EAP-Response/Identity message tothe BNG, wherein the message includes the user name.

Step 506: The BNG encapsulates the EAP-Response/Identity message into aRADIUS Access-Request message to send to the AAA server.

Step 507: The AAA server generates a Challenge, and sends the Challengeto the BNG through a RADIUS Access-Challenge message to the BNG; the BNGextracts the Challenge from the RADIUS Access-Challenge message, andthen sends it to the user terminal through an EAP-Request/MD5-Challengemessage.

Step 508: The user terminal extracts the Challenge after receiving theEAP-Request/MD5-Challenge message, and performs MD5 calculation to itsown user password and the Challenge to obtain an encrypted userpassword, namely Challenged-Pass-word; then, the user terminal carriesthe Challenged-Pass-word in the EAP-Request/MD5-Challenge message tosend to the BNG; the BNG sends the Challenge, the Challenged-Pass-wordand the user name to the AAA server through the Radius message.

Here, the Challenge, the Challenged-Pass-word and the user name areauthentication information of user.

Step 509: After receiving the Radius message, the AAA server extractsthe authentication information of user to perform MD5 calculation, so asto determine whether the user is valid; if the user is valid, the AAAserver sends an authentication success message to the BNG, wherein theauthentication success message carries the user subscriptioninformation; or else, the AAA server sends an authentication failuremessage to the BNG, and the flow ends.

Wherein, the user subscription information includes: user subscriptionbandwidth, priority and encryption key, wherein the encryption key isthe PSK or the PMK.

Step 510: After receiving the authentication success message, the BNGextracts the user subscription information from it, and sends the usersubscription information to the user terminal trough the EAPauthentication success message.

Step 511: The BNG confirms the AC to which the user terminal belongsthrough the MAC address of the user terminal and/or the user sidelogical interface information (here, the user side logical interface canalso be the user side physical port) of the BNG; then, the BNG sends theuser subscription information to the AC through the Radius CoA messageor the Diameter CCA message.

Step 512: The AC sends the user subscription information to the AP bymeans of CAPWAP or TR-069.

Step 513: The AP configures according to the user subscriptioninformation; specifically, the AP performs a bandwidth and priorityconfiguration of an air interface according to the user subscriptionbandwidth and priority.

Step 514: The AP and the user terminal conduct key negotiation accordingto the encryption key (PSK or PMK) to obtain the encryption key PTK,wherein the encryption key PTK is used for encrypting data flow betweenthe AP and the user terminal.

Furthermore, the AP can also generate an encryption key GMK according tothe PMK to send to the user terminal, and then conducts with theterminal to obtain an encryption key GTK for encrypting a multicastmessage.

Step 515: The user terminal applies to the BNG for an IP address throughthe DHCP protocol; the BNG sends an accounting start request to the AAAserver while assigning the IP address to the user terminal; the AAAserver responds accounting start success to the BNG, and the BNG sendsthe IP address to the user terminal.

Step 516: The user accesses a network.

Embodiment 2

A scenario that the embodiment is applicable is shown in FIG. 3; the APand the AC are connected through a BRAS device; the AC controls that themessage of the AP is forwarded through the BRAS; the user accesses themessage of a network side not through the AC; the WLAN device is the AP;as shown in FIG. 6, the flow of WLAN user fixed network access includesthe following steps.

Step 601: The following configurations are performed in the AP:configuring the AP as the authentication client end, and configuring theBNG as the authentication server end of the AP.

Step 602: The following configurations are performed in the BNG:configuring the BNG as the authentication server end, and configuringthe AP as the authentication client end of the BNG.

Step 601 and Step 602 are executed in a random order.

Step 603 to Step 604: The user terminal obtains an IP address form theBNG through the DHCP protocol; and the user accesses the message of thenetwork side by redirecting to the portal server through the BNG device.

Step 605: The user authentication is performed among the user terminal,the portal server, the BNG and the AAA server;

specifically, the user terminal accesses the portal server to input auser name and a password; the portal server sends the user name and thepassword to the AAA server; and the AAA server informs the BNG ofsuccessful user authentication after the user authentication issuccessful.

Step 606: After receiving the authentication success message, the BNGextracts the user subscription information from it, and sends the usersubscription information to the user terminal through the EAPauthentication success message.

Step 607: The BNG confirms the AP to which the user terminal belongsthrough the MAC address of the user terminal and/or the user sidelogical interface information (here, the user side logical interface canalso be the user side physical port) of the BNG; then, the BNG sends theuser subscription information to the AP through the Radius CoA messageor the Diameter CCA message.

Step 608: The AP configures according to the user subscriptioninformation; specifically, the AP performs a bandwidth and priorityconfiguration of an air interface according to the user subscriptionbandwidth and priority.

Step 609: The AP and the user terminal conduct key negotiation accordingto the encryption key (PSK or PMK) to obtain the encryption key PTK,wherein the encryption key PTK is used for encrypting data flow betweenthe AP and the user terminal.

Furthermore, the AP can also generate the encryption key GMK accordingto the PMK to send to the user terminal, and then conducts with theterminal to obtain the encryption key GTK for encrypting a multicastmessage.

Step 610: The user accesses a network.

Embodiment 3

After accessing a network, the user changes the user subscriptioninformation on line by accessing the portal server; the process that theAP acquires the user subscription information is shown in FIG. 7,including:

Step 701: The user accesses the portal server, and changes the usersubscription information (such as the user subscription bandwidth andpriority) on line.

Step 702: The portal server sends the changed user subscriptioninformation to the AAA server;

here, the user subscription information can be sent by using the privateprotocol message between the portal server and the AAA server.

Step 703: The AAA server sends the changed user subscription informationto the BNG through the Radius CoA message or the Diameter CCA message.

Subsequently, there are two ways that the BNG sends the changed usersubscription information to the AP.

1. When the WLAN device is the AC, the way includes:

Step 704 a: the BNG sends the changed user subscription information tothe AC through the Radius CoA message or the Diameter CCA message;

Step 704 b: the AC sends the user subscription information to the AP bymeans of CAPWAP or TR-069.

2. When the WLAN device is the AP, the way includes:

Step 704: the BNG sends the changed user subscription information to theAP through the Radius CoA message or the Diameter CCA message;

Step 705: the AP configures according to the user subscriptioninformation; specifically, the AP performs a bandwidth and priorityconfiguration of an air interface according to the user subscriptionbandwidth and priority.

In this case, there is no need to conduct key negotiation.

For implementing the above method, the present disclosure also providesa system for a WLAN user to access a fixed network; as shown in FIG. 8,the system includes: a BNG 10 and a WLAN device 20;

the BNG 10 is configured to, after the WLAN user authentication issuccessful, send the obtained user subscription information to the AP;

the WLAN device 20 is configured to perform related configurationaccording to the user subscription information.

Wherein, the BNG 10 is further configured to, after the WLAN userauthentication is successful, send the user subscription information tothe WLAN user terminal through the EAP authentication success messagewhile sending the obtained user subscription information to the WLANdevice.

When the WLAN device 20 is the AC, the BNG 10 is further configured toconfirm the AC to which the WLAN user terminal belongs, and send theuser subscription information to the AC through the Radius CoA messageor the Diameter CCA message;

the AC is configured to send the user subscription information to the APby means of CAPWAP or TR-069;

or,

when the WLAN device 20 is the AP, the BNG 10 is further configured toconfirm the AP to which the WLAN user terminal belongs, and send theuser subscription information to the AP through the Radius CoA messageor the Diameter CCA message.

The BNG 10 is further configured to confirm the AC or the AP to whichthe WLAN user terminal belongs through the MAC address of the WLAN userterminal and/or the user side logical interface or physical portinformation of the BNG.

The AP is further configured to perform a bandwidth and priorityconfiguration of an air interface according to the user subscriptionbandwidth and priority in the user subscription information, and conductkey negotiation with the WLAN user terminal according to the encryptionkey in the user subscription information to obtain the encryption keyPTK; wherein, the encryption key is the PSK or the PMK.

After the user subscription information is changed,

when the WLAN device 20 is the AC, the BNG 10 is further configured tosend the changed user subscription information to the AC through theRadius CoA message or the Diameter CCA message;

the AC is further configured to send the user subscription informationto the AP by means of CAPWAP or TR-069;

or,

when the WLAN device 20 is the AP, the BNG 10 is further configured tosend the changed user subscription information to the AP through theRadius CoA message or the Diameter CCA message.

The above is only the preferred embodiment of the present disclosure andnot intended to limit the scope of the claims of the present disclosure.

What is claimed is:
 1. A method for a Wireless Local Area Network (WLAN)user to access a fixed network, comprising: after the WLAN user isauthenticated successfully, sending, by a Broadband Network Gateway(BNG), obtained user subscription information to a WLAN device; andafter the WLAN device performs related configuration according to theuser subscription information, accessing, by a WLAN user terminal, anetwork.
 2. The method according to claim 1, wherein before theauthentication of the WLAN user, the method further comprises:configuring the BNG as an authentication server end, and configuring theWLAN device as an authentication client end.
 3. The method according toclaim 1, wherein the WLAN device is an Access Controller (AC) or anAccess Point (AP).
 4. The method according to claim 1, wherein after theWLAN user is authenticated successfully, while the BNG sends theobtained user subscription information to the WLAN device, the methodfurther comprises: sending, by the BNG, the user subscriptioninformation to the WLAN user terminal through an ExtensibleAuthentication Protocol (EAP) authentication success message.
 5. Themethod according to claim 1, wherein, when the WLAN device is the AC,the step of sending, by the BNG, the obtained user subscriptioninformation to the WLAN device comprises: confirming, by the BNG, the ACto which the WLAN user terminal belongs, and sending the usersubscription information to the AC through a Radius CoA message or aDiameter CCA message; and sending, by the AC, the user subscriptioninformation to the AP by means of Control And Provisioning of WirelessAccess Points Protocol (CAPWAP) or Technical Report-069 (TR-069); orwhen the WLAN device is the AP, the step of sending, by the BNG, theobtained user subscription information to the WLAN device comprises:confirming, by the BNG, the AP to which the WLAN user terminal belongs,and sending the user subscription information to the AP through theRadius CoA message or the Diameter CCA message.
 6. The method accordingto claim 5, wherein the step of confirming, by the BNG, the AC or the APto which the WLAN user terminal belongs comprises: confirming, by theBNG, the AC or the AP to which the WLAN user terminal belongs through aMedia Access Control (MAC) address of the WLAN user terminal and/or userside logical interface or physical port information of the BNG.
 7. Themethod according to claim 6, wherein the step of performing, by the WLANdevice, related configuration according to the user subscriptioninformation comprises: the AP performs a bandwidth and priorityconfiguration of an air interface according to a user subscriptionbandwidth and a priority in the user subscription information; and theAP and the WLAN user terminal conduct a key negotiation according to anencryption key in the user subscription information to obtain anencryption key PTK; the encryption key is a Pre-shared Key (PSK) or aPairwise Master Key (PMK).
 8. The method according to claim 1, whereinafter the WLAN device performs related configuration according to theuser subscription information, the method further comprises: applyingto, by the WLAN user terminal, the BNG for an IP address through aDynamic Host Configuration Protocol (DHCP) protocol, and accessing anetwork after obtaining the IP address; or, before the authentication ofthe WLAN user, the method further comprises: applying to, by the WLANuser terminal, the BNG for an IP address through the DHCP protocol. 9.The method according to claim 8, wherein after the WLAN user accesses anetwork, the method further comprises: accessing, by the WLAN user, aportal server, and changing the user subscription information on line;sending, by the portal server, the changed user subscription informationto an Authentication, Authorization and Accounting (AAA) server; andsending, by the AAA server, the changed user subscription information tothe BNG through the Radius CoA message or the Diameter CCA message. 10.The method according to claim 9, further comprising: sending, by theBNG, the changed user subscription information to the WLAN device,comprising: when the WLAN device is the AC, sending, by the BNG, thechanged user subscription information to the AC through the Radius CoAmessage or the Diameter CCA message; and sending, by the AC, the usersubscription information to the AP by means of CAPWAP or TR-069; or whenthe WLAN device is the AP, sending, by the BNG, the changed usersubscription information to the AP through the Radius CoA message or theDiameter CCA message.
 11. A system for a Wireless Local Area Network(WLAN) user to access a fixed network, comprising: a WLAN BroadbandNetwork Gateway (BNG) and a WLAN device; the BNG is configured to, afterthe WLAN user is authenticated successfully, send obtained usersubscription information to the WLAN device; and the WLAN device isconfigured to perform related configuration according to the usersubscription information.
 12. The system according to claim 11, wherein,the BNG is further configured to, after the WLAN user is authenticatedsuccessfully, send the user subscription information to the WLAN userterminal through an Extensible Authentication Protocol (EAP)authentication success message while sending the obtained usersubscription information to the WLAN device.
 13. The system according toclaim 12, wherein, when the WLAN device is an Access Controller (AC),the BNG is further configured to confirm the AC to which the WLAN userterminal belongs, and send the user subscription information to the ACthrough a Radius CoA message or a Diameter CCA message; the AC isconfigured to send the user subscription information to the AP by meansof Control And Provisioning of Wireless Access Points Protocol (CAPWAP)or Technical Report-069 (TR-069); or when the WLAN device is an AccessPoint (AP), the BNG is further configured to confirm the AP to which theWLAN user terminal belongs, and send the user subscription informationto the AP through the Radius CoA message or the Diameter CCA message.14. The system according to claim 13, wherein, the BNG is furtherconfigured to confirm the AC or the AP to which the WLAN user terminalbelongs through a Media Access Control (MAC) address of the WLAN userterminal and/or user side logical interface or physical port informationof the BNG.
 15. The system according to claim 14, wherein, the AP isfurther configured to perform a bandwidth and priority configuration ofan air interface according to a user subscription bandwidth and apriority in the user subscription information, and conduct a keynegotiation with the WLAN user terminal according to an encryption keyin the user subscription information to obtain an encryption key PTK;the encryption key is a Pre-shared Key (PSK) or a Pairwise Master Key(PMK).
 16. The system according to claim 15, wherein, after the usersubscription information is changed, when the WLAN device is the AC, theBNG is further configured to send the changed user subscriptioninformation to the AC through the Radius CoA message or the Diameter CCAmessage; the AC is further configured to send the user subscriptioninformation to the AP by means of CAPWAP or TR-069; or when the WLANdevice is the AP, the BNG is further configured to send the changed usersubscription information to the AP through the Radius CoA message or theDiameter CCA message.